Seal and scraper arrangement



Nov. 15, 1960 R. c. ULM 7 2,960,252

- SEAL AND SCRAPER ARRANGEMENT Filed Aug. 1, 1957 IN VENTOR.

Unite tates SEAL AND SCRAPER AGEMENT Filed Aug. 1, 1957, Ser. No. 675,672

4 Claims. (Cl. 220-26) The invention relates to a floating roof arrangement and particularly to a novel seal shoe assembly therefor.

As is well known in the art, field storage tanks generally comprise a cylindrical tank shell having a roof arranged to float on product stored therein. Of course, these structures are relatively large and in order for the roof to freely move vertically in the tank shell without binding, a peripherally spaced aperture must be provided between the roof rim and tank shell. To reduce product loss from evaporation and to avoid unreasonable contamination of the product, this annular space must be sealed and it has been the practice of the art to provide movable roof supported sealing arrangements for this purpose.

Of course, tanks of this nature are used to store a variety of products. In many instances the product stored has elements therein which tend to come out of solution and adhere to various portions of the tank providing a wax-like coating thereon. These coatings, especially any that adhere to the side walls of a tank, have caused considerable difficulty from a maintenance standpoint as far as the floating roof tank arrangement is concerned. Buildup of such coatings creates a serious and expensive maintenance problem. It has been found that the shoe tends to scrape some of this material from the tank shell depositing same on the roof. These deposits must be frequently removed for sanitary reasons, to prevent clogging of drains which could result in roof sinkage and to avoid injury to the tank arrangement and operating personnel. The scraping action of the shoe on the inner periphery of the tank shell has also sometimes interfered with the proper action of the sealing mechanisms.

Accordingly, it is a general object of the invention to avoid the difliculties mentioned by providing a novel seal arrangement for use on a floating roof that will scrape product coatings from the inner periphery of the tanks shell and maintain same in a reasonably clean condition.

It is a specific object of the invention to provide an arrangement of the type described that removes unwanted tank shell coatings as the roof moves downwardly in the tank causing the removed material to be deposited on the bottom of the tank.

These and other objects of the invention will become apparent in the course of the following description and from an examination of the concerned drawings wherein:

Figure 1 is a fragmentary side elevational view of a floating roof arrangement embodying the invention,

Figure 2 is a fragmentary sectional view taken along lines 2-2, and

Figure 3 is an enlarged fragmentary sectional view taken along lines 33 of Figure 2.

Describing the invention in detail, it will be understood that a conventional cylindrical floating roof tank shell is fragmentarily indicated at 2. The tank shell 2 contains product shown at 4, said product fioatingly sup porting the fragmentarily illustrated roof indicated generally at 6. The roof 6 may be of any conventional atent O 2,960,252 Patented Nov. s, 1950 variety comprising a bottom 8 and a peripherally upstanding rim 10, said rim being normally spaced from the tank shell 2. To seal the space between the rim 1t} and the tank shell 2, a sealing mechanism indicated at 12 is provided, said mechanism comprising a ring 14 composed of a plurality of shoes 16 in horizontally aligned relationship (not shown) as is familiar to those skilled in the art. In the normal position each shoe 16 abuts and continuously engages the inner periphery of the tank shell 2. To support each shoe 16 and therefore the entire ring, a plurality of hangers 18 may be provided of any conventional variety. Normally, each hanger 18 has a lower end pivoted as at 20 adjacent the lower portion of the roof 6 and has an upper end pivotally connected as at 22 to the related shoe 16. To complete the seal, an annular fabric covering member 24 is provided, said covering member having its opposite edges tightly secured to the upper edge of the shoe 16 as at Mind the upper part of the rim 10 as at 28. In order to maintain a reasonable amount of pressured engagement between the shoes 16 and the tank shell 2 and to aid in centrally locating the roof, a plurality of pusher arrangements may be provided and in the preferred embodiment of the invention each pusher arrangement comprises a coiled spring 30 interposed between and in pressured engagement with the rim 10 and the shoe 16. Here the coiled spring 30 is fixedly held in position by bosses 32., 3'4 operatively connected to the rim 10 and shoe 16.

As earlier noted certain products tend to build up coatings on the tank shell and to avoid the difliculties heretofore mentioned, the invention provided a plurality of unique scraper means indicated generally at 36, fixedly secured to the lower edge of each shoe 16. In a preferred embodiment of the invention the scraper means comprises a plurality of flap-like scrapers 38, 33 in immediately adjacent edge to edge relationship along the lower edge of each shoe 16. Directing attention to Figure 3, it will be seen that each flap 38 comprises a U shaped member 40 arranged to receive the lower flange of a channel member 42, said channel member being secured to the shoe 16 by means of a bolt 44, whereby the U-shaped element 40 is tightly clamped against the adjacent portion of the shoe. Extending downwardly from the U-shaped element 40 and in cantilever fashion is the flap scraper 38. As illustrated, each scraper 38 presents at the lowest extremity thereof an edge 48 arranged so that it is in spring-like or pressured engagement with the inner periphery of the shell 2. The spring effect of the scraper 38 serves the additional function of maintaining the edge 48 in contact with the inner periphery of the shell should an uncentering roof movement in the tank tend to enlarge the annular space at any point between the rim 10 and the tank shell. This avoids any localized build up of coating material due to the disengagement of the scraper with the tank shell. It will also be noted that the bosses 34 which retain the springs 30 are connected to the channels 42 whereby the pressured action of the pusher springs 30 are concentrated against the shoe in the area immediately adjacent the scraper flaps 38. This further tends to maintain intimate engagement between the scraper flaps 38 and the inner periphery of the shell.

It is also to be preferred that the scraper means 36 engage the tank shell adjacent but above the product level. This location increases the efliciency of the scraping action as it avoids wax deposits on the lower shoe and scraper arrangement and on the shell above the scraper during downward roof movement.

In operation of the invention it will be noted that scraper flaps tend to flexibly override any coating material during upward movement of the roof and thus avoiding any scraping action during such movement. How-- ever, upon downward movement of the roof the intimate contact between the edges 48 of the scraper flaps 38 effectively cleans the inner periphery of the tank shell of all foreign material, it being noted that the material will be caused to drop downwardly into the product 4 and from whence it falls to the tank bottom where it may be effectively cleaned in the usual manner. Thus it will be seen that the invention provides efficient scraping and cleaning action for-the inner periphery of the tank shells in those instances where stored product tends to build up on the contactedportionsvof the containing vessel and thereby avoid the difiiculties heretofore mentioned.

The invention as disclosed is by way of illustration and not limitation and may be subject to various modifications without departing from the spirit thereof or the scope of the appended claims.

What is claimed is:

1. In a seal arrangement for use in association with a field storage tank having a roof arranged to float on liquid stored therein, the combination of a peripherally arranged annular upstanding rim on the roof, a plurality of annularly arranged seal shoes spaced from the rim and engaging the inner wall of the tank, flexible fabric seal means having opposite edges thereof continuously connected to the shoes and the rim, hanger means t support the shoes from the roof having opposed ends pivoted to the roof and shoes respectively, scraper means secured to and projecting below the lower edge of the shoes and comprising a plurality of supporting members connected to and projecting inwardly from the lower portion of the shoes and each having a supporting portion, a plurality of flexible sheet metal elements respectively supported by said supporting members, each of said elements having an inwardly directed part engageable with the supporting portion of its associated supporting member and a second part projecting downwardly and outwardly below the lower edge of its associated shoe and in angular relation with the tank shell, said second part being flexible to be biased in downwardly scraping engagement with the inner surface of said tank shell, said elements coacting to provide a ganerally annular scraper for scraping substantially the entire wall of the tank irrespective of its surface irregularities, and resilient biasing means operatively interposed between the roof and the shoes immediately adjacent to said elements urging said shoes and roof apart, thereby to further assure that the second parts of said elements are biased into engagement with the inner wall of the tank.

2. In a sealing arrangement for use in association with a field storage tank having an opened upper end and a floating roof arranged to float on liquid stored therein, the combination of annular shoe means including a lower annular portion in engagement with the inner wall of the tank, sealing means interconnecting the shoe means and the roof, means for supporting the shoe means from the roof, and scraper means secured to and projecting below the lower annular portion to remove deposits on the inner wall of said tank during downward movement of the floating roof, said scraper means including supporting means attached to and projecting inwardly from said lower annular portion, a plurality of flexible sheet metal elements carried by said supporting means and each including a first portion projecting inwardly from said lower annular portion to be in engagement with an inwardly projecting part of said supporting means, each of said elements further including a second portion projecting downwardly and outwardly below the lower edge of the annular portion in acute angular relation with the wall of the tank, said second portion being biased outwardly into scraping engagement with the inner surface of said tank shell by its inherent resiliency to follow the surface of the tank wall irrespective of its irregularities, said elements coacting to provide a generally annular scraper for scraping the whole wall, and biasing means operatively interposed between the roof and the lower annular portion immediately adjacent to the elements urging the shoe means and the roof apart, thereby to further assure that the second portions of said elements are biased into engagement with the inner wall of the tank.

3. The arrangement of claim 2 wherein said supporting means is provided with an anchor portion which includes said inwardly projecting part and wherein said sheet metal element includes a reverse portion comprising an extension of said first portion, said reverse portion and first portion coacting with said anchor portion to support said element from said supporting means.

4. The arrangement of claim 3 wherein there is additionally provided means for urging said anchor portion toward said annular portion to clamp said reverse portion and first portion between said supporting means and annular portion.

References Cited in the file of this patent UNITED STATES PATENTS 1,463,268 Hufi July 31, 1923 2,685,503 Knecht Aug. 3, 1954 2,801,763 Ulm Aug. 6, 1957 2,846,110 Stoyer Aug. 5, 1958 

